1. Field of the Invention
This invention relates in general to the electrical switching of signals and power in microelectronics circuits.
2. Description of the Related Art
Relays generally use a relatively small electrical current to switch a larger one. Relays usually are operated by electromagnetic solenoids: these are difficult to manufacture in very small size.
Relays are of several kinds. AC, DC, latching and non-latching, multiple or single pole.
Solid state relays exist. In these a voltage controls whether a circuit is conductive or not. These are made as microelectronic components. The disadvantage is that a voltage drop occurs across the component such that it consumes power even when inactive. It works only when electrical voltage is applied.
A relay has two circuits, one that operates the actuator and another that acts as a conductive path for power to be used elsewhere.
A relay requires an actuator, making it different from a switch that may be manually operated. Conventional macroscopic relays use solenoids. Miniature relays use electrostatic, piezoelectric, and thermal actuators. Two types of thermal actuators exist: those based on differential thermal expansion, and those utilizing shape memory alloys. It is known that shape memory alloy actuators have higher work output per unit mass than other actuators.